用另一个字符串中的另一个字符替换字符串中的字符 [英] Replacing a character in a string with another character from another string

问题描述

我试图最终用另一组String替换一个句子.但是我在尝试用另一个String的另一个字符替换String中的char时遇到了障碍.

I am trying to eventually replace a sentence with another set of String. But I hit a roadblock while trying to replace a char in a String with another character of another String.

这是我到目前为止所拥有的.

Here's what I have so far.

String letters = "abcdefghijklmnopqrstuvwxyz";
String encode = "kngcadsxbvfhjtiumylzqropwe";
// the sentence that I want to encode
String sentence = "hello, nice to meet you!";

//swapping each char of 'sentence' with the chars in 'encode'
for (int i = 0; i < sentence.length(); i++) {
    int indexForEncode = letters.indexOf(sentence.charAt(i));
    sentence.replace(sentence.charAt(i), encode.charAt(indexForEncode));
}

System.out.println(sentence);

这种替换字符的方法不起作用.有人可以帮我吗?

This way of replacing characters doesn't work. Can someone help me?

推荐答案

原因

sentence.replace(sentence.charAt(i), encode.charAt(indexForEncode));

不起作用是因为 String 是不可变的(即，它们永远不变).因此， sentence.replace(...)实际上并没有改变 sentence ；而是返回新的 String .您可能需要编写 sentence =句子.replace(...)才能将结果捕获回 sentence .

doesn't work is that Strings are immutable (i.e., they never change). So, sentence.replace(...) doesn't actually change sentence; rather, it returns a new String. You would need to write sentence = sentence.replace(...) to capture that result back in sentence.

好的，字符串101:类已关闭(;->).

OK, Strings 101: class dismissed (;->).

现在，尽管如此，您确实不想继续将部分编码的句子重新分配给自己，因为您几乎可以肯定会发现自己重新编码了您已经编码的句子.最好保留 sentence 的原始形式，同时一次将编码的字符串建立一个字符，如下所示:

Now with all that said, you really don't want want to keep reassigning your partially encoded sentence back to itself, because you will, almost certainly, find yourself re-encoding characters of sentence that you already encoded. Best to leave sentence in its original form while building up the encoded string one character at a time like this:

StringBuilder sb = new StringBuilder();
for (int i = 0; i < sentence.length(); i++){
    int indexForEncode = letters.indexOf(sentence.charAt(i));
    sb.append(indexForEncode != -1
            ? encode.charAt(indexForEncode)
            : sentence.charAt(i)
    );
}
sentence = sb.toString();

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